Nine patients with distal ulcerative colitis refractory to standard therapy were treated with intrarectal instillation of a sodium butyrate solution and 5-ASA. A marked clinical, endoscopical and, to a smaller extent, histological improvement was observed in seven of nine patients. The clinical improvement usually occurred within the second week of therapy, and thus earlier than in previous cases treated with butyrate alone. This preliminary experience suggests that the combined butyrate-5-ASA treatment may prove a useful therapeutic tool in refractory distal ulcerative colitis and possibly increase the effectiveness of the individual therapeutic regimens.